The proposed research has a strong experimental base which rests on three areas of experimental advances. The first of these is the finding that diabetic patients with nephropathy exfoliate at least five types of epithelial cells into their urine which can be grown in tissue cultures. The second finding is that employment of serum-free hormonally-defined growth medium allows the selective explanation of specific epithelial cell types from the human kidney. The success of this approach is documented by the recent optimization of culture conditions allowing the proliferation of human proximal convoluted tubule cells to 50 generations in cell culture. The third finding is that elevated glucose concentrations chosen to resemble the diabetic state have profound effects upon cellular metabolism in culture cells. This is best exemplified by the finding of a large decrease in ion transport properties by proximal convoluted tubule cells exposed to as little as 200 mg glucose/100 ml growth medium. The specific aims of the proposed research are: 1) to continue to develop new culture systems representative of specific areas of the human kidney; 2)\to test the hypothesis that the time of initiation of cell exfoliation, the type of cell exfoliated and the number of exfoliated will yield new information on the progression of kidney involvement in diabetes mellitus; and 3) to test the adverse effects of elevated glucose concentrations on kidney cell responsibilities when maintained in tissue culture and also as a function of cell exfoliation into the urine of diabetic patients. The successful completion of these efforts will yield a model system for the study of kidney epithelial cell responsibilities in normal and disease situations. An increased understanding fo the characteristics of these cells when exposed to elevated glucose concentrations will yield new insights of importance regarding diabetic nephropathy.